In a BGP VPLS network, transit routers must determine
the payload for hash calculations for load balancing. While parsing
an MPLS encapsulated packet for hashing, a transit router can incorrectly
calculate an Ethernet payload as an IPv4 or IPv6 payload if the first
nibble of the destination address MAC is 0x4 or 0x6, respectively.
This false positive can cause out-of-order packet delivery over a
pseudowire. This issue can be avoided by configuring a BGP VPLS PE
router to request that other BGP VPLS edge (VE) routers insert a control
word between the label stack and the MPLS payload.
Warning: If you attempt to set a control word in a VPLS network
that contains a VE router that does not support a control word, the
pseudowire will not come up. To ensure that the pseudowire comes up,
be sure that all VE routers in the VPLS network support the presence
of a control word.
Before configuring support for a control word
in a BGP VPLS network, ensure that the router meets the following
requirements:
MX Series router running Junos OS Release 14.1 or later
and containing one of the following Flexible PIC Concentrators: ADPC,
NPC, or I-Chip
OR
M320 router running Junos OS Release 14.1 or later and
containing either the I-Chip or the Trio
To configure a VE router to expect a control word between
the label stack and the MPLS payload:
- At the
[edit routing-instances] hierarchy level
in configuration mode, set control-word for the VPLS protocol
for the specified routing instance.[edit routing-instances]
user@host# set routing-instance-name protocols vpls control-word
For example:
[edit routing-instances]
user@host# set vpls1 protocols vpls control-word
- If you are setting
control-word on a Trio-based
MPC on an MX Series router, set no-ether-pseudowire to
omit the IP payload over the Ethernet pseudowire from the hash key.[edit forwarding-options]
user@host# set enhanced-hash-key family mpls no-ether-pseudowire
- Verify the configuration.
[edit routing-instances]
user@host# show
vpls1 {
protocols {
vpls {
control-word;
}
}
}[edit forwarding-options]
user@host# show
enhanced-hash-key {
family mpls {
no-ether-pseudowire;
}
}
- Repeat the configuration on each VE router in the BGP
VPLS network.
- Run
show vpls connections instance routing-instance-name extensive to verify the presence of a control word for the
pseudowire.For example:
user@host# show vpls connections instance vpls1 extensive
Layer-2 VPN connections:
Legend for connection status (St)
EI -- encapsulation invalid NC -- interface encapsulation not CCC/TCC/VPLS
...
PF -- Profile parse failure PB -- Profile busy
Legend for interface status
Up -- operational
Dn -- down
Instance: vpls1
...
connection-site Type St Time last up # Up trans
1 rmt Up May 21 10:08:34 2013 2
Remote PE: 192.0.2.0, Negotiated control-word: Yes
